IAD99FA008

The Learjet was participating in water ingestion tests, which required multiple landing rolls through a diked pool on the runway. On one of the landing rolls, the airplane's left main landing gear and nose landing gear tracked through the pool, while the right main landing gear tracked outside the pool. The airplane veered to the left, departed the left side of the runway, and struck a pickup truck parked adjacent to the runway. The airplane came to rest inverted and on fire. Formal hazard identification and risk management procedures were not employed and no alignment cues were in place on the runway to facilitate pool entry alignment. Further, the accident truck, other vehicles, heavy equipment, and personnel were placed hundreds of feet inside the FAA recommended runway-safe and object-free areas during the test.

History of flight

On October 27, 1998, at 1456 eastern standard time, a Learjet 45 registered in the experimental category, N454LJ, was destroyed after a loss of control during landing roll and collision with a ground vehicle at the NASA Wallops Flight Facility (WAL), Wallops Island, Virginia. The certificated airline transport pilot (ATP) was not injured. The ATP rated copilot and the flight test engineer received minor injuries. There were no injuries on the ground. Visual meteorological conditions prevailed for the local test flight that originated at WAL, at 1449. No flight plan had been filed for the flight conducted under 14 CFR Part 91.

According to the pilot, the airplane and crew were involved in flight test certification for a new nose wheel tire. For the test, the airplane was passed through a "pool'' or "trough" of water on the runway at different speeds. Then data was collected using video, still photography, and on-board diagnostic equipment. The airplane was loaded, configured, and operated inside and outside the weight-and-balance and performance envelopes of a Learjet 45 registered in the normal category. The pool was 30 feet wide, 200 feet long, formed with flexible rubber dikes, and contained 3/4 of an inch of standing water. Beginning the day prior to the accident, the crew had successfully completed 10 passes through the test pool.

In a written statement, the pilot described the flight prior to the accident. He further described adjustments made on final approach to reach the intended touchdown point; 1,000 feet beyond the approach end of runway 22. The pilot said:

"Initial alignment during rollout was uneventful. [Thrust reversers] were selected to, and maintained at, idle reverse until a point where I thought we needed to select maximum reverse to get full reverse thrust and enter the pool at target speed of 80 knots. As soon as the [thrust reversers] reached full reverse, the aircraft pulled to the right. Left rudder was input to realign the fuselage.

"At pool arrival, the aircraft had almost re-aligned and I left left rudder and nose wheel steering in to attempt to drift the aircraft left a couple of feet, since it appeared the right mains were on the edge of the pool. The aircraft began a fishtail to the right (nose left) and I immediately input right rudder and stowed the [thrust reversers]. I believe this arrested the fishtail, but a runway [left] side departure was evident."

The pilot described the maneuvers necessary to avoid striking test participants, vehicles, and equipment along the left side of the runway after the airplane departed the pool. However, he was unable to prevent the right wing from striking an unmanned pickup truck parked on an intersecting runway. After collision with the truck, the wings separated from the airplane, the fuselage rolled inverted, and spilled fuel ignited.

In a written statement, the co-pilot said:

"The aircraft entered the trough with maximum thrust reversers selected. [I] gave a "mark" to specify trough entry. My impression was that the aircraft had a slight right drift at water entry. Immediately after entering the trough, the aircraft yawed left. While this yaw was apparent, [I] felt the aircraft was controllable. The aircraft corrected back to the right slightly then yawed hard left. At this point, [I] felt the aircraft was in an uncontrollable hydroplaning condition and that the aircraft was going to depart the runway."

A review of videotape revealed that left rudder inputs and movement of the airplane's nose to the left were evident just prior to pool entry. The nose wheel and rudder remained deflected as the airplane entered the pool. The airplane continued to yaw left as the tail "fishtailed" to the right. The airplane departed the left side of the runway, struck the pickup truck, and came to rest inverted and on fire.

When questioned about the airworthiness of the airplane, both pilots stated there were no deficiencies with the airplane or its performance.

The accident occurred during the hours of daylight approximately 37 degrees, 56 minutes north latitude, and 75 degrees, 27 minutes west longitude.

Personnel information

The pilot held an Airline Transport pilot certificate with ratings for airplane single engine land, multi-engine land, and instrument airplane. He also held a flight instructor certificate for airplane single engine land, multi-engine land, and instrument airplane.

His most recent Federal Aviation Administration (FAA) First Class Medical Certificate was issued on November 17, 1997.

The pilot reported 13,073 hours of flight experience, 767 hours of which were in make and model.

The co-pilot held an Airline Transport pilot certificate with ratings for airplane multi-engine land, and instrument airplane. He also held a commercial pilot certificate with ratings for airplane single engine land, rotorcraft-helicopter, and instrument helicopter.

His most recent Federal Aviation Administration (FAA) First Class Medical Certificate was issued on June 22, 1998.

The co-pilot reported 4,202 hours of flight experience, 93 hours of which were in make and model.

Aircraft information

The airplane was a 1996 Learjet 45, registered in the experimental category to Learjet, Inc., for the purposes of research and development.

The airplane was on an annual inspection program with the most recent inspection completed on October 12, 1998. The airplane had accrued approximately 5 hours of flight time since that date and had a total of 339.4 hours at the time of the accident.

Meteorological information

The weather reported at Wallops Island was scattered clouds at 1,800 feet with winds from 070 degrees at 12 knots.

Aerodrome information

The National Aeronautics and Space Administration operated the Wallops Flight Facility, of the Goddard Space Flight Center for the purposes of flight testing. NASA, the military, various branches of the federal government, and private industry use the facility.

At the airport were three intersecting runways oriented 10-28, 17-35, and 04-22 degrees. The runways were 8,000, 4,820, and 8,750 feet respectively. All three runways were 150 feet wide and constructed of asphalt and concrete. Runway 04-22 was equipped with a water ingestion trough for water ingestion testing.

Wreckage and impact information

The wreckage was examined at the scene on October 28, 1998, and all major components were accounted for at the scene. Examination of the runway and the test pool revealed the tire tracks from the accident run were still visible. The tire tracks revealed that upon pool entry, the left main gear and the nose gear tires tracked through the pool, while the right main gear tires tracked outside the pool.

The wreckage path was approximately 300 feet long and oriented approximately 180 degrees. The wreckage path was measured from the point of collision with the truck and the final resting point of the fuselage. The truck was originally parked on the left side of runway 22 at the intersection of runway 17-35.

The truck was completely destroyed by frontal collision and post crash fire and came to rest approximately 150 feet down the wreckage path. The airplane came to rest inverted, oriented approximately 240 degrees, and was also consumed by post crash fire. Fire destroyed the airplane's exterior on the north side of the wreckage and consumed the interior. The south side of the wreckage was unmarked by fire damage.

The emergency exit door on the south side of the fuselage was undamaged and unopened.

Aircraft rescue fire fighting (ARFF)

A review of videotapes revealed ARFF units arrived at the accident site approximately 40 seconds after the accident. Water was dispensed from the first unit approximately 1 minute after its arrival. However, the unit, an Amertek C-4000 pumper truck, was unable to dispense water onto the